Conventional marine seismic surveying uses a seismic source and a number of streamers towed behind a seismic survey vessel. These streamers have sensors that detect seismic energy for imaging the formations under the seafloor. Deploying the streamers and sources and towing them during a survey can be relatively straightforward when operating in open waters with moderate swells or the like.
Marine locations covered by ice, debris, large swells, or other obstacles can make surveying more difficult, expensive, or even impossible. In icy waters, for example, the seismic survey vessel must break through ice and traverse waters filled with ice floes. The noise generated by ice impacts can complicate the seismic record produced.
Additionally, the ice floes on the water's surface make towing the source and streamers more difficult and prone to damage. For example, any components of the system at the water's surface can encounter ice, become bogged down, and lost. In addition, any cables or towlines coming off the vessel even from slipways can collect ice at the surface. Likewise, ice pulled under the hull and rising behind the vessel can shear away these cables and lines.
Some approaches for performing seismic surveys in icy regions known in the art are disclosed in U.S. Pat. Nos. 5,113,376 and 5,157,636 to Bjerkoy. To date, however, the problems associated with marine seismic surveying in icy or obstructed waters have not been significantly addressed.
The subject matter of the present disclosure is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.